Control operator for hydraulic pumps



Aug. 11, 1953 W. R. TUCKER AL CONTROL OPERATOR FOR HYDRAULIC 'PUIIPS Filed Nov. 28, 1951 IN VENT CR5 TVrren R Thole:-

BY //m ATTORNEY Patented Aug. 11, 1953 CONTROL OPERAT OR FOR HYDRAULIC MPS Warren R. Tucker and Glen Richard Pittman,

Mount Gilead, Ohio, assignors to H-P-M Development Corporation, Mount Gilead, Ohio, a

corporation of Delaware Application November 28, 1951, Serial No. 258,708

1 Claim. 3

The present invention relates generally to fluid-actuated pumps or motors, and more specifically to an improved fluid pressure-responsive control or operator for hydraulic pumps.

In the past, it has been common practice to employ in connection with hydraulic pumps a servo-motor control comprising one or more fiuid-pressure-responsive piston areas arranged to shift the flow-controlling member of the pump between various concentric and eccentric positions with respect to the primary rotor of the pump and thereby to vary the stroke of the pumping pistons and the consequent volumetric output of the pump. Ordinarily, the piston stages of the servo-motor control are arranged so as to shift the flow-controlling member of a pump between desired positions providing for full volumetric flow of fluid in either direction, in the case of reversible variable delivery pumps, and to a neutral or no-delivery position, wherein the flow-controlling member occupies a substantially concentric position with reference to the rotor of the pump. Various automatic control systems have been employed to exert fluid pressure upon the piston stages of a servo-motor control in accordance with varying positions of a ram or motor under control of the pump, or in accordance with variations in pressure at given points within the hydraulic system actuated by the pump.

It follows, therefore, that the primary object of the present invention is to provide an. improved hydraulic control operator arranged to be connected with the usual servo-motor controls of an hydraulic pump, and which functions both selectively and automatically to control the volumetric output of the pump.

It is another object of the invention to provide a remote hydraulic control operator which may be selectively operated from a relatively low pressure pilot system, independent of the main hydraulic system of the pump to be controlled, and which also incorporates means automatically responsive to pressure conditions within the main hydraulic system for automatically controlling the volumetric output of a pump independently of the separate selectively operable pilot-actuated control members.

For a further and more detailed understanding of the present invention and the various additional objects and advantages derived therefrom, reference is to be had to the following description and the accompanying drawing, wherein: the single figure is a diagrammatic viewof a hydraulic control operator iormed'in accordance Iii Cal

with the present invention and operatively connected with a reversible, variable delivery .hydraulic pump.

Referring now to the drawing, the numeral l0 designates generally the outer casing of a reversible-flow, variable delivery hydraulic pump. In the usual manner, the pump comprises an annular flow control ring II .in which is rotatably supported an annular secondary pump rotor 12 carrying a plurality of radially disposed inwardly projecting pumping pistons l3. The pistons I! are reciprocable within a like member of radially disposed cylinders l4 formed in a cylindrical primary rotor I5. The cylinders I 4 are arranged to selectively communicate with the inlet-outlet ports 16 formed in a stationary valve pintle l'l about which the primary rotor I5 is rotated by means of an electric motor or other suitable power source, not shown.

In the form of pump shown in the drawing, the flow control ring H is engaged on one side by a fluid pressure-actuated plunger 18 which is movable within a servo-motor housing 20 and in response to fluid pressure conditions established in the servo-motor housing and controlled by a valve-actuatingrod Ill. The details of construction of the servo-motor, as shown in the drawing, correspond to that described in United States Patent No. 2,184,665 issued to Walter Ernst December-26, 1939. Arranged in diametrically opposed relation to the servo-motorplunger I8 is a second plunger 22 which engages the flow control ring H, and which is connected to one end of a coil compression spring 23 mounted within a second casing extension 24. The tension of the spring 23 may be adjusted, in the usual manner, by means of a hand wheel 25 which extends exteriorly of the casing extension 24. The spring 23 and its plunger .22 are arranged to urge the flow control ring H of the" pump leftwardly as viewed in the drawing, and to a position providing for maximum delivery of fluid pressure outwardly through a first inletoutlet conduit 26, communicating at one end with one of the inlet-outlet ports 16 of thestationary valve pintle.

As shown in the drawing, the inlet-outlet conduit 26 communicates, as at '21, with the ramadvancing area 28 of a reciprocating hydraulic ram .29, .the latter being carried in wiping engagement withthe inner walls of a hydraulic cylinder '30. In this assembly, the ram-retracting area 3| of the motor communicates withone end ofra second inlet-outletconduit '32 connected -with. the opposite inlet-outlet port iii of the pump. In the usual manner, make-up fluid is supplied to and exhausted from the ram-advancing area by way of a surge and prefill valve 33 which communicates with a fluid reservoir 33a mounted atop the cylinder 30. As the flow control ring ll of the pump is shifted from its full line position, as shown in the drawing, to an extreme right-hand position, the flow of fluid through the pump will be reversed to introduce pressure fluid within the conduit 32 and the ramretracting area 3| of the motor.

It will be understood that the foregoing description of the pump I and of the hydraulic motor or ram is common to many types of hydraulic systems and, per se, constitutes no part of the present invention.

In accordance with this invention, a lever 34 is pivotally connected with the outer end of the servo-motor rod or shaft |9, as at 35, and is arranged for rocking movement about a pivot point 36 to move the rod l9 inwardly or outwardly with respect to the servo-motor casing 20 to thereby control movement of the flow control ring H of the pump between its various concentric and eccentric positions with respect to the rotor of the pump. The pivot point 36 is provided by a stationary bracket 31 rigidly secured to the outer end portion of the casing extension 20. The opposite end portion of the lever 34 is pivotally connected with a link 38 carried upon the upper end of a. rod 39 which, in turn, is pivotally connected, as at 40-, with the remotely extending actuator rod or shaft 4| of the present hydraulic control operator.

The control operator of the present invention comprises a main casing 42 having a plurality of laterally extended boss formations 43 formed with bolt-receivingopenings 44 through which anchoring bolts, not shown, may be passed to secure the casing to a stationary support, such as the frame portion of a hydraulic press. The casing 42 is formed with a first bore 45 which communicates at one end with a relatively reduced diameter bore or passage 46 through which the actuator rod 4| extends, and terminates at its opposite end in a diametrically enlarged annular port 41. The port 41 communicates with a radially disposed conduit-receiving connection 48 terminating at the outer periphery of the casing 42. The first cylinder bore 45 is in direct communication with a second and slightly larger diameter cylinder bore 49 which, in turn, communicates with a third and still larger bore 50 formed in the lower end of the casing 42. The bore 50 is likewise provided with an inlet-outlet port terminating in a conduit connection 52.

The lower end of the larger cylindrical bore 50 is closed by one end of a cylindrical casing extension 53 which is rigidly secured, as by cap screws 54, to the lower end of the casing 42. Advantageously, the mating end portions of the casing 42 and the casing extension 53 may be provided with cooperative shouldered regions arranged to receive and compress an annular sealing ring 55 which establishes a fluid-tight connection between the casing 42 and the extension 53. The extension 53 is formed with an axially disposed and relatively small diameter cylinder bore 56 which terminates toward the lower end of the extension 53 in an enlarged chamber 51. An inlet-outlet port 58 is provided in the lower end wall of the extension 53 and communicates with the chamber 51.

Slidably carried in wiping engagement with the walls of the first cylinder bore 45 is a fluid-pressure-responsive piston 59 connected directly with the lower end of the actuator rod 4|. The opposite ends of the piston 49 provide differential pressure areas upon the piston, with the lower pressure area being substantially greater than that of the upper pressure area, due to the reduction in area at the upper end of the piston occasioned by the rod 4|. The second and relatively larger cylinder bore 49 of the casing 42 receives a second fluid-pressure-responsive piston 59 whose upper end is beveled, as at 6!, for engagement with the lower pressure surface of the piston 59. The lower end portion of the piston 59 is provided with a relatively diametrically en-- larged annular shoulder 62 which provides upon its under surface a pressure-responsive area of reater size than the beveled area 6| of the piston. Also, due to the diametric enlargement of the shouldered portion 62 of the piston 60, movement of the piston 60 in an upward direction is limited to the distance between the inner end of the casing extension 53 and the inwardly projecting ledge 63 formed between the bores 49 and 5E]. The limit of movement of the smaller piston 59 is equal to the distance between the beveled end portion 6| of the piston 69, when the latter occupies its lowermost position as shown in the drawing, and the upper end wall of the casing 42. This movement of the piston 59 is suihcient to actuate the rod |9 to cause the servo-motor mechanism to shift the flow control ring I of the pump between its extreme right and left-hand eccentric positions with respect to the primary rotor to cause a reversal in the direction of flow of fluid between opposite full-delivery positions of the pump.

The upper end of the smaller cylinder bore is provided with an inlet-outlet port 64 which is in constant communication, by means of a conduit 65, with the discharge of a pilot pump 66 arranged to draw fluid from a reservoir 61. Thus, the upper surface of the piston 59 is constantly subjected to fluid pressure derived from the pump 66 and is urged downwardly of the casing 42. To cause movement of the piston 59 in the opposite or upward direction, the port 41 is connected with one end of a conduit 68 which extends to the discharge port 69 of a three-way solenoid-operated valve 10. The valve 10 is further provided with an inlet port 1| which is connected by way of a conduit 12 with the supply conduit 65 lead ing from the discharge of the pump 66. The valve 10 is operable, upon energization of the solenoid 13, to connect the inlet port 1| with the outlet port 69, and thereby to introduce fluid under pressure of the pump 66 into the port 41 and cylinder bore 49. The valve 19 is operable, upon deenergization of the solenoid 13, to disconnect the outlet port 69 from the inlet port H and to establish communication between the outlet port 69 and an exhaust conduit 14. Thus, for example, when it is desired to shift the flow control ring I of the pump to its extreme right-hand position, reversing the direction of the flow of fluid from that disclosed in the drawing, the solenoid 13 of the Valve 19 is energized to introduce fluid pressure within the cylinder bore 49 and beneath the lower surface of the piston 59. Due to the increased area of the lower surface of the piston 59 over the upper surface thereof, the piston is caused to move upwardly within the bore 45 and is maintained at its upper limit of movement against the wall of the casing defining the end of the bore 45.

The larger cylinder bore has its port connected by way of a conduit 15 with the outlet port 16 of a second solenoid-actuated valve 11.

The valve 11 is substantially identical to the valve and is provided with an inlet port 19 which is connected by the conduit 19 to receive the discharge of the pump 66, the valve TI being provided with an exhaust conduit 89 and a solenoid 8|. In operation, the valve 11, in. its deenergized condition, establishes communication between the inlet port 18 and the outlet port 16 to pass fluid pressure from the pump 66 into the cylinder bore 50 of the actuator, and conversely, upon energization, the outlet port 16 is connected with the exhaust conduit 80 to relieve pressure fluid from the pump 66 within the bore 59, such pressure is transmitted to the relatively larger lower face of the shoulder 62. to cause the pistons 69 and 59 to rise. vertically within the casing 92 in opposition to fluid pressure exerted upon the upper surface of the piston 59, and to a position where the shoulder 62 engages the ledge 93 of the casing and the flow-controlling member of the pump is shifted to a neutral or no-delivery position. Thus, it will be seen that the two separate pistons 59 and 60 provide for selective movement of the actuator rod 19 of the servo-motor of the pump to provide for full reversal of the pump, or shifting of the pump between a full delivery position and a neutral or no-delivery position. This control of the pump is accomplished through selective energization and deenergization of the valves 19 and TI, and it will be understood that the'solenoids of these valves may, in accordance with usual practice, be automatically energized inresponse to the actuation of one or more switches, not shown, arranged to be opened or closed in accordance with the predetermined movement of the ram 29, or in accordance with predetermined pressures at various points within the hydraulic system.

To provide for the automatic shifting of the flow control member I I of the pump to a neutral or pressure-holding position in response to a predetermined build-up in pressure within a given area of the hydraulic system, there is provided a third plunger or piston 82 which is reciprocable within the bore 56 of the casing extension 53. The piston 82 is arranged to abut the lower surface of the piston 69 at one end and communicates at its opposite end with the pressure chamber 51. The port 59 is connected 7 with one end of a conduit 83 which has its opposite end connected, as at 84, with the inletoutlet conduit 26 extending between the pump [9 and the ram-advancing area 28 of the motor.

Interposed. within the conduit 83 is a solenoidactuated shut-off valve 85 which may be conditioned, by energization of its associated solenoid, to either open or close the conduit 83. Positioned within the conduit 83 between the valve 95 and the chamber 51 is a pressure relief valve which is adjustable to determine the pressure required to open the same and permit fluid to pass in a direction toward the chamber 51. Arranged in bypassing relation to the valves 85 and 96 is a conduit 81 in which is interposed a check valve 88 which opens only in a direction toward the inlet sides of the valves 85 and 89 to permit fluid to be exhausted from the chamber 5'! in a direction toward thepump 10.

In operation, assuming that the ram 29 is employed to actuate the members of a hydraulic press, and it is desired to initiate an advancin stroke of the ram 29, the latter is maintained in its uppermost position, as shown in the drawing, by positioning the flow control member H of the :pump .in its neutral position providing forno displacement of .fiuid through either of the conduits .26 or '32. To maintain the flow control member II in its neutral position, the valve 11 is deenergized to establish communication between the discharge of the pump 66 and the lower surface of the larger piston 69. At this time, the valve 10 is also deenergized .to connect the lower surface of the smaller piston 59 with exhaust, pressure from the pump 66 being constantly introduced into the bore 45 to react upon the upper surface of the piston 59. With the-valves HI-and 11 in this condition, the piston .ismaintained in its uppermost position at which time the piston 59 occupies an intermediate position within the bore 45. Energizationof the valves 11 establishes communication between the lower surface of the piston 69 and the exhaust conduit 89, thus permitting the pressure from the pump 66 acting upon the upper surface of the piston 59 to move the pistons 59 and 69 to their lowermost positions as shown in the drawing,tand to move the actuator rod 19 of the servo-motor outwardly and thereby to shift the flow control member H of the pump to its extreme left-hand position providing for full displacement of fluid into the ram-advancing area 29. Thus, the ram 29 is caused to advance rapidly within the cylinder 60 to initiate a pressing cycle which continues until the ram bottoms, or until sufiicient pressure is built up within the ram-advancing area and the discharge of the pump 19 to open the pressure relief valve 96 and admit'pressure fluid into the chamber 51 beneath thesmaller plunger 82. When the pressure within the discharge of the pump ill increases to a predetermined high pressure, the plunger 82 is moved upwardly with a consequent upward movement of the pistons 59 and 69 in opposition to the pressure of fluid acting upon the upper surface of the piston 59. This upward movement shifts the rod [9 inwardly sufliciently to place the pump on a pressure holding cycle sufiicient to maintain a given holding pressure within the discharge of the pump to compensate for any leakage or slippage within the system. When it is desired to retract the ram 29 after its pressing cycle, the valve 10 is energized to cause pressure fluid from the pump 66 to be introduced within the bore 49 to react against the larger lower surface of the piston 59 and move the same to its extreme upward position within the bore 45 providing for a reversal in the direction of fluid flow from the pump I9. Thus, fluid discharged from the pump is introduced within the ram-retracting area 3| of the motor by Way of the conduit 32 to retract the ram 29 to its uppermost position as shown in the drawing. The valve 19 is then deenergized to once again initiate an advancing stroke, or to maintain the ram in its upper stationary position.

In view of the foregoing, it will be seen that the present invention provides an improved hydraulic control actuator for variable delivery hydraulic pumps which is characterized by its versatility in operation in controlling selectively and automatically the various positions of the flow-controlling member of a pump in accordance with the desired operation of the pump. Further, in view of the employment of a piston which is responsive to a predetermined build-up in pressure within the hydraulic system controlled by the pump to automatically shift the pump to a holding position, in addition to piston stages which are selectively operable to shift the pump between neutral and full delivery positions, it is possible to obtain a given holding pressure within the hydraulic circuit to compensate for any slippage within the pump or leakage within a circuit controlled thereby. Further, the present actuator may be arranged in remote relation to the pump which is controlled thereby to thus reduce installation problems with respect to various hydraulic circuits.

While a single representative illustration of the present control actuator has been disclosed in detail, it will be understood that various modifications may be resorted to without departing from the spirit of the invention or the scope of the following claim.

We claim:

A hydraulic control operator comprising a casing formed with a first cylinder bore, a second relatively diametrically enlarged cylinder bore communicating with and forming a longitudinal continuation of said first cylinder bore, a pressure chamber communicating with the second cylinder bore at the end thereof opposite the first cylinder bore, a first inlet-outlet port communicating with the first cylinder bore, a second inlet-outlet port communicating with the second cylinder bore at the end thereof communicating with the first cylinder bore and a third inletoutlet port communicating with said pressure iamber; a first piston reciprocable in the first bore of said casing and having a relatively reduced diameter actuator rod extending axially outwardly from one end thereof and outwardly through said casing, said first piston being movable differentially within the first cylinder bore of said casing in response to the introduction of pressure fluid within the first and second ports of said casing; a second piston reciprocable in the second bore of said casing and having a first end surface arranged to abut the end of said first piston opposite the actuator rod and a second diametrically enlarged end portion extending within the pressure chamber of said casing, said second piston being operable, in response to the introduction of fluid pressure within the third port of said casing to move said first piston and its actuator rod in opposition to fluid pressures exerted upon said first piston; and pistoncylincler means connected with said casing and closing one end of the pressure chamber formed therein, said means comprising a fluid-pressureresponsive piston of smaller diameter than said first and second pistons and arranged in axially abutting relation to said second piston and movable to shift said first and second pistons and the actuator rod longitudinally of said casing.

WARREN R. TUCKER. GLEN RICHARD PI'I'TMAN.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,239,882 Davis Apr. 29, 1941 2,302,922 Tucker Nov. 24, 1942 2,417,858 Becker Mar. 25, 1947 2,443,345 Ernst June 15, 1948 2,447,707 May Aug. 24, 1948 2,455,837 Waldie Dec. 7, 1948 

